A conventional apparatus for manufacturing a composite metal wire by using a two wheel type continuous extrusion apparatus comprises two rotary wheels having grooves on the outer periphery thereof, provided symmetrically relative to an extruding direction of the composite metal wire, a fixed shoe block having an arc-edge surface for closing partially the grooves of the rotary wheels to provide two passage-ways, a nipple having an aperture through which a core metal wire is supplied, two position-changeable abutments each pressed into the groove of the corresponding rotary wheel to close the passage-way, and two adjusting bolts each adjusting a contact pressure of the corresponding abutment to the corresponding rotary wheel, wherein the shoe block is provided with a die which is positioned on the side of extruding the composite metal wire in a covering chamber which is defined between the die and the nipple and communicates with the two passage-ways.
In operation, two aluminum rods are supplied into the two passage-ways, respectively, while the two rotary wheels are rotated to apply a dragging force to the two aluminum rods, so that the supply of plasticized aluminum to the covering chamber is interrupted by the abutments, in which a steel core wire supplied from the nipple is coated with the plasticized aluminum to be extruded from the die.
Thus, a composite metal wire having the steel core wire coated with a covering layer of aluminum is manufactured by using the two wheel type continuous extrusion apparatus.
In this two wheel type continuous extrusion apparatus, the covering chamber is connected via covering material inlet apertures to the passage-ways, wherein the covering material inlet apertures are provided vertical to the extrusion direction of the composite metal wire to be positioned on a line connecting the rotary axes of the rotary wheels.
In another conventional apparatus for manufacturing a composite metal wire by using a two wheel type continuous extrusion apparatus, a covering chamber is provided on the opposite side of supplying covering material rods relative to the line connecting the rotary axes of the rotary wheels, such that the covering material inlet apertures are inclined relatively to the extrusion direction of the composite metal wire. In addition, the combination of abutments and a nipple is replaced by an abutment which is formed with a nipple in an integral manner.
According to the former conventional apparatus for manufacturing a composite metal wire, however, there is a disadvantage in that it is difficult to suppress the amount of the burr formation, when it is increased due to the abrasion, the deformation, etc. of parts of the apparatus such as the rotary wheels, because the position change of the abutments is small, which results in unsufficient adjustment which cannot provide a predetermined seal effect between the grooves of the rotary wheels and the abutments. Consequently, the parts must be replaced earlier by new ones. This results in a trouble-some and more frequent disassembling operation of the fixed shoe block, the position-changeable abutments, etc. Further, there is a disadvantage in that the dimension precision of the parts which is required to manufacture a composite metal wire having a predetermined precision which is sought by experiments, so that it takes a long time to adjust the apparatus appropriately. Still further, there is a disadvantage in that a pull-in force (a horizontal component force) of the fixed shoe block, caused by the rotation of the rotary wheels is directly applied to the adjusting bolts and a support block for supporting the adjusting bolts, so that the mechanical strength of the support block must be large.
On the other hand, the latter conventional apparatus for manufacturing a composite metal wire by using a two wheel type continuous extrusion apparatus is more practical than the former conventional one, because the sealing contact pressure is easily adjusted therein, for the reason that the two separate abutments are largely changed in position, and because the dimension precision of the parts can be relieved to some extent. However, there is a disadvantage in that a force for sustaining the abutments must be large, because the covering material inlet apertures are inclined on the opposite side of the covering material supplying rods relatively to the rotary axis connecting line of the rotary wheels. Further there is a disadvantage in that apparatus cost becomes high, because the total configuration of the fixed shoe block and the abutments becomes large in an integral block, and is therefore divided to be assembled by two sections. As a matter of course, the assembling and disassembling operation of the two-divided sections is required, which results in the necessity of the use of a longer time and skilled workers.